Modification method of Pd / C catalyst and application of Pd / C catalyst in hydrodehalogenation reaction

Abstract

The invention provides a modification method of a Pd / C catalyst. The method comprises the following steps: (1) carrying out first drying treatment on the Pd / C catalyst; (2) mixing the catalyst obtained in the step (1), S-containing amino acid or a derivative thereof, an organic nitrogen source and a solvent, and carrying out heat treatment, wherein the mass ratio of the S-containing amino acid or the derivative thereof to the organic nitrogen source to the catalyst to the solvent is (0.01-0.1): (0.05-0.5): 1: (5-50); (3) separating and washing the catalyst obtained in the step (2), and carrying out second drying treatment; and (4) roasting the catalyst obtained in the step (3) to obtain the modified Pd / C catalyst. The invention also provides a hydrodehalogenation method of halogenated organic matters. According to the method, the Pd / C modified catalyst is used for reaction.

Description

Technical Field

[0001] The invention relates to the field of catalysts, in particular to a method for modifying a commercial Pd / C catalyst and application of the modified catalyst in a hydrodehalogenation reaction of a halogenated organic compound. Background Art

[0002] Halogenated organic compounds are important chemical raw materials, but polyhalogenated organic compounds are extremely harmful to the environment due to their inherent difficulty in degradation and harmfulness. In addition, the value and market demand of polyhalogenated organic compounds are often low, and most of the industrial treatment methods for these polyhalogenated organic compounds are treated as waste. If one or more halogen atoms on polyhalogenated organic compounds can be removed by appropriate means, polyhalides with no industrial use can be converted into useful low-halides, which will help waste treatment, save corporate costs, and achieve the concept of green production.

[0003] At present, common hydrodehalogenation catalysts are mainly based on Pd, Pt, Rh and Ni catalysts. Compared with Ni-based catalysts, precious metal catalysts have higher activity and stability under mild conditions, among which Pd catalysts have better hydrodehalogenation activity. Pd / C commercial catalyst is one of the most studied hydrogenation catalysts, and it is also widely used in the field of hydrodehalogenation. Pd / C catalysts are very active in hydrodehalogenation, but there are great problems in selectivity and stability. The common deactivation mechanisms of Pd-based catalysts are mainly: loss of active components, metal agglomeration and sintering, metal poisoning and carbon deposition. In the prior art, the stability problem is improved by a modification method that combines sulfur sources such as SCl2, S2Cl2, CS2, thiophene, dimethyl sulfide, H2S, and methyl mercaptan into a supported Pd-based catalyst, but this modification method will reduce the catalytic activity and selectivity to a certain extent.

[0004] Therefore, there is an urgent need in the art to develop an improved method for modifying a Pd / C catalyst, wherein the catalyst obtained by the method has both stability and high selectivity and can be applied to different hydrodehalogenation reactions. Summary of the invention

[0005] The first aspect of the present invention provides a method for modifying a Pd / C catalyst, the method comprising the following steps:

[0006] (1) subjecting the Pd / C catalyst to a first drying treatment;

[0007] (2) mixing the catalyst obtained in step (1), an S-containing amino acid or its derivative, an organic nitrogen source and a solvent and subjecting them to heat treatment, wherein the mass ratio of the S-containing amino acid or its derivative, the organic nitrogen source, the catalyst and the solvent is 0.01-0.1:0.05-0.5:1:5-50;

[0008] (3) separating, washing and performing a second drying treatment on the catalyst obtained in step (2);

[0009] (4) calcining the catalyst obtained in step (3) to obtain a modified Pd / C catalyst.

[0010] The second aspect of the present invention provides a modified Pd / C catalyst prepared by the modification method of the present invention.

[0011] The third aspect of the present invention provides a method for the hydrodehalogenation of halogenated organic matter, wherein the method uses the Pd / C type modified catalyst described herein to carry out the reaction.

[0012] A fourth aspect of the present invention provides a hydrodehalogenation product prepared according to the hydrodehalogenation method described herein. DETAILED DESCRIPTION

[0013] The inventors of the present application discovered that by modifying the commercial Pd / C catalyst with S and N using S-containing amino acids or their derivatives and an organic nitrogen source, the selectivity of hydrogenation of halogen-containing compounds and the stability of the catalyst can be improved through a simple modification process, and the present invention was completed on this basis.

[0014] "Scope" disclosed herein is defined in the form of lower limit and upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a particular range. The scope defined in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a particular parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0015] In this application, unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined with each other to form a new technical solution.

[0016] In this application, unless otherwise specified, all technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0017] In the present application, unless otherwise specified, all steps mentioned herein may be performed sequentially or randomly, but are preferably performed sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0018] In this application, unless otherwise specified, the terms "include" and "comprising" mentioned herein may be open-ended or closed-ended. For example, the terms "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0019] In the description of this article, it should be noted that, unless otherwise specified, "above" and "below" are inclusive of the number itself, and "several" in "one or several" means two or more.

[0020] In the description herein, unless otherwise specified, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0021] Herein, unless otherwise specified, percentage (%) or part refers to percentage by weight or part by weight relative to the composition.

[0022] Herein, if there is no contrary description, the sum of the contents of the various components in the composition is 100%.

[0023] Herein, if there is no contrary description, the sum of the parts of each component in the composition may be 100 parts by weight.

[0024] In this context, unless otherwise specified, "a combination thereof" means a multi-component mixture of the elements described, for example a mixture of two, three, four and up to the maximum possible multi-component mixture.

[0025] If not specifically stated, the terms "a" or "an" used in the present specification means "at least one".

[0026] Herein, unless otherwise stated, all reactions are carried out at normal temperature and pressure.

[0027] The first aspect of the present application provides a method for modifying a Pd / C catalyst, the method comprising the following steps:

[0028] (1) subjecting the Pd / C catalyst to a first drying treatment;

[0029] (2) mixing the catalyst obtained in step (1), an S-containing amino acid or its derivative, an organic nitrogen source and a solvent and subjecting them to heat treatment, wherein the mass ratio of the S-containing amino acid or its derivative, the organic nitrogen source, the catalyst and the solvent is 0.01-0.1:0.05-0.5:1:5-50;

[0030] (3) separating, washing and performing a second drying treatment on the catalyst obtained in step (2);

[0031] (4) calcining the catalyst obtained in step (3) to obtain a modified Pd / C catalyst.

[0032] "Pd / C catalyst" is a supported catalyst prepared by loading the active component palladium on a carrier activated carbon in some way. Pd / C catalyst can catalyze the hydrogenation of olefins, alkynes, ketones, nitriles, imines, azides, nitro compounds, benzene rings and heterocyclic aromatic compounds. It can also be used for the hydrogenolysis of cyclopropane, phenyl derivatives, epoxides, hydrazines and halides. It can also be used for the dehydrogenation of aromatic compounds and the deacylation of aldehydes.

[0033] The method of the present application can modify Pd / C catalysts. The Pd / C catalysts can be commercial Pd / C catalysts available on the market, or catalysts prepared by loading the active component palladium on a carrier activated carbon in any manner. The Pd / C catalysts can be in powder form or in columnar form.

[0034] In a specific embodiment of the present application, the Pd loading in the Pd / C catalyst is 0.1-2.0%, and the specific surface area is ≥400m 2 / g.

[0035] Preferably, the Pd / C type catalyst contains a catalytic promoter component. In a specific embodiment of the present application, the catalytic promoter component includes one or more of Pt, Ni, Co, Au, Ag, Cu, and Fe, wherein the Pd content is >50%, based on the total weight of the metal components.

[0036] "S-containing amino acid" refers to an amino acid with sulfur-containing side chains, mainly including cystine and methionine. In the present application, S-containing amino acids and derivatives thereof can be used to improve Pd / C catalysts. In a specific embodiment of the present application, the S-containing amino acids and derivatives thereof include one or more of cysteine, methionine, cystine, acetylcysteine, sulfo-cysteine, benzyl-cysteine, ethyl-cysteine, (2-carboxyethyl)-cysteine, glutathione, and adenosylmethionine. Preferably, the S-containing amino acids and derivatives thereof include cystine, cysteine, acetylcysteine, (2-carboxyethyl)-cysteine, and sulfo-cysteine; most preferably, the S-containing amino acids and derivatives thereof include cysteine ​​and acetylcysteine.

[0037] "Organic nitrogen source" provides N doping to the catalyst support. In the present application, "organic nitrogen source" can be protein and its hydrolyzate, including polypeptides, amino acids, etc. In a specific embodiment of the present application, the organic nitrogen source includes one or more of glutamic acid, lysine, glycine, histidine, asparagine, and arginine. Preferably, the organic nitrogen source includes glutamic acid and asparagine; most preferably, the organic nitrogen source includes glutamic acid.

[0038] In the present application, the combination of S-containing amino acid and organic nitrogen source to modify Pd / C catalyst can improve the catalytic selectivity and stability of active metal.

[0039] In a specific embodiment of the present application, the weight ratio of the S-containing amino acid to the organic nitrogen source is 1:0.5-5, preferably 1:1-3, and more preferably 1:1.75-2.25.

[0040] In a specific embodiment of the present application, based on the weight of the Pd / C catalyst, the amount of the S-containing amino acid is 1-10% by weight, preferably 2-7% by weight, and the amount of the organic nitrogen source is 2-25% by weight, preferably 3-20% by weight, and most preferably 5-15% by weight.

[0041] In a specific embodiment of the present application, the mass ratio of the S-containing amino acid, the organic nitrogen source, the catalyst and the solvent is 0.01-0.1:0.02-0.25:1:5-50.

[0042] In the present application, a solvent is used to dissolve the amino acid during the heat treatment to help the reactants mix fully. There is no particular limitation on the solvent used, as long as it can achieve the purpose of dissolving. In a specific embodiment of the present application, the solvent includes one or more of water, methanol, ethanol, isopropanol, and acetonitrile. In the present application, the water can be deionized water, distilled water, ultrapure water, etc.

[0043] In the present application, the heat treatment can be carried out by a heat treatment method commonly used in the art, including but not limited to heating, heat preservation, etc. In a specific embodiment of the present application, the heat treatment temperature is 150-250°C, preferably 180-220°C, and the reaction time is 2-24h, preferably 5-20h.

[0044] In the present application, there is no particular limitation on the specific means and methods for separation, washing and drying of the catalyst, as long as the purpose of the present application can be achieved.

[0045] The drying step can be performed in an inert gas atmosphere or vacuum drying. In a specific embodiment of the present application, the first drying is performed in an inert gas atmosphere, and the inert gas includes one or more of N2, He, Ne and Ar.

[0046] There is no particular limitation on the specific drying temperature and time, as long as the purpose of the present application can be achieved. In a specific embodiment of the present application, in step (1), the first drying temperature is 30-150°C, preferably 40-120°C, and the first drying time is 4-48h, preferably 6-40h.

[0047] In a specific embodiment of the present application, the second drying temperature is 60-150° C., preferably 80-120° C., and the second drying time is 2-36 hours, preferably 4-30 hours.

[0048] In a specific embodiment of the present application, the solvent used for washing includes one or more of water, methanol, ethanol, isopropanol, and acetonitrile.

[0049] In one example of the present application, the amount of the solvent used in the heat treatment is 5-50 times, preferably 10-40 times, of the catalyst by weight.

[0050] In one example of the present application, the amount of the washing solvent used in step (3) is 1-10 times, preferably 3-6 times, of the catalyst by weight.

[0051] In the present application, the specific means and methods of catalyst roasting are not particularly limited, as long as the purpose of the present application can be achieved. In a specific embodiment of the present application, the roasting is carried out in an inert gas, and the inert gas includes one of N2, He, Ne and Ar. In the present application, "roasting" can adopt the conventional roasting temperature in the art. The roasting temperature is 400-600°C, and the roasting time is 2-24h.

[0052] In a specific example of the present application, the temperature rise process in the roasting stage can be a single gradient temperature rise or a double gradient temperature rise. The single gradient temperature rise program includes heating to the roasting temperature at a heating rate of 0.2 to 1.0 ° C / min for roasting; the double gradient temperature rise program includes heating to a gradient temperature of 200 to 300 ° C at a heating rate of 0.5 to 2 ° C / min, maintaining for 2 to 12 hours, and then heating to the roasting temperature at a heating rate of 4 to 10 ° C / min for roasting.

[0053] The Pd / C catalyst prepared by the method described in the present application has high catalytic activity and improved stability in the hydrodehalogenation reaction, and can prepare catalytic hydrodehalogenation products with high selectivity.

[0054] Another aspect of the present application provides a method for hydrodehalogenation of halogenated organic matter, wherein the method uses the Pd / C type modified catalyst described herein to carry out the reaction.

[0055] In the present application, the "halogenated organic compound" refers to a compound formed by replacing a functional group in an organic compound with a halogen atom, such as fluorine, chlorine, bromine, or iodine. The halogenated organic compound includes but is not limited to chloroalkanes, chloroaromatic hydrocarbons, bromoalkanes, and the like. In a specific embodiment of the present application, the halogenated organic compound includes one or more of chlorobenzene, 1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3-dichlorobenzene, 1,2,3-trichlorobenzene, 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, 1,2,3,4,5-pentachlorobenzene, hexachlorobenzene, and chloronaphthalene, chlorobiphenyl, chlorofluorene, and bromoalkanes.

[0056] In the present application, the hydrodehalogenation method can be carried out by a kettle hydrogenation process or a fixed bed hydrogenation process. The kettle hydrogenation process comprises reacting the halogenated organic matter with hydrogen in the presence of the Pd / C type modified catalyst and a base. The fixed bed hydrogenation process comprises reacting the halogenated organic matter with hydrogen in the presence of the Pd / C type modified catalyst.

[0057] In a specific embodiment of the present application, in the kettle hydrogenation process, the concentration of the alkali is 0.1-10 wt %, the reaction temperature is 50-150° C., and the hydrogen pressure is 0.2-2.5 MPa.

[0058] In a specific embodiment of the present application, in the fixed bed hydrogenation process, the reaction temperature is 150-250° C., the reaction space velocity is 0.2-2 h-1, and the hydrogen / halogenated organic molar ratio is 3-30:1.

[0059] Taking 1,2,4-trichlorobenzene as an example, 1,2,4-trichlorobenzene is subjected to catalytic hydrogenation and dehalogenation to remove a chlorine atom to obtain dichlorobenzene, which is a low-halogen product required in industry. Chlorobenzene is also generated during the hydrogenation process, and excessive hydrogenation will generate benzene and cyclohexane. The Pd / C modified catalyst obtained in this application can improve the selectivity of dichlorobenzene and prevent excessive hydrogenation in the hydrogenation and dehalogenation reaction.

[0060] The advantages of the present invention are:

[0061] 1. The present invention utilizes the special structure of S-containing amino acids to modify the Pd / C catalyst, and improves the anti-loss and anti-sintering capabilities of Pd by N-doping the carrier. At the same time, the moderate coordination of S to Pd improves the anti-poisoning ability of Pd, effectively improving the stability of the Pd / C catalyst in the hydrodehalogenation reaction.

[0062] 2. While maintaining high activity, the catalyst can prevent over-hydrogenation in the hydrodehalogenation reaction to a certain extent.

[0063] 3. The commercial Pd / C catalyst modification method of the present invention is applicable to various types of Pd / C catalysts and can be applied to a variety of reaction processes, facilitating large-scale promotion.

[0064] Unless otherwise specified, the various raw materials of the present application can be obtained from the market; or prepared according to conventional methods in the art. Unless otherwise defined or specified, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any methods and materials similar or equivalent to those described herein can be applied to the methods of the present invention. Other aspects of the present invention are obvious to those skilled in the art due to the disclosure of this article.

[0065] Example

[0066] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods for which specific conditions are not indicated in the following examples are usually measured according to national standards. If there is no corresponding national standard, then proceed according to general international standards, normal conditions, or according to the conditions recommended by the manufacturer. Unless otherwise stated, all parts are by weight, all percentages are by weight, and the polymer molecular weight is the number average molecular weight.

[0067] Raw material sources and preparation

[0068] Main reagents for the experiment

[0069]

[0070]

[0071] Main experimental instruments

[0072] Instrument Name model Manufacturer Electronic balance JA31002 Shanghai Yitian Scientific Instrument Co., Ltd. Fixed bed reactor HF-V1 Shanghai Baikal Technology Group Co., Ltd. Tank reactor BKLS-5L Shanghai Baikal Technology Group Co., Ltd. Gas Chromatograph 7890A Agilent Technologies

[0073] Gas chromatography test conditions

[0074]

[0075] Calculation method of conversion rate and selectivity: Collect the liquid after reaction, analyze the components by Agilent 7890 gas chromatograph, use hydrogen flame detector (FID), and calculate the concentration of each component by external standard method, where

[0076] Conversion rate (%) = 1-(substrate concentration after reaction / substrate concentration before reaction) × 100%,

[0077] Selectivity (%) = 1-(concentration of corresponding substance / sum of concentrations of all generated substances) × 100%.

[0078] Catalyst stability test method:

[0079] Catalyst life (h) refers to the length of time the catalyst is in operation when the reaction conversion rate and reaction selectivity decay to less than or equal to 80%.

[0080] In the fixed bed hydrogenation process, the life of the catalyst is evaluated in the following manner: Catalyst life (h) refers to the operating time during which the reaction conversion rate and reaction selectivity decay are less than or equal to 80%.

[0081] In the kettle reactor hydrogenation process, the catalyst can be recycled, and the number of applications is evaluated in the following way: the catalyst is recycled and fed again for reaction. The number of applications for life evaluation refers to the maximum number of applications of the catalyst when the reaction conversion rate and reaction selectivity decay are less than or equal to 80%. The higher the number of applications, the higher the stability of the catalyst.

[0082] Example I-1

[0083] The Pd / C modified catalyst was prepared as follows:

[0084] Take 100.0g of commercial Pd / C catalyst GX-20240907-1 (granular catalyst, Pd loading is 0.5%, the co-catalyst component is Pt, the content of Pd in ​​the metal component is 75%, the specific surface area is 924.7m 2 / g), heated to 120°C in a N2 atmosphere and dried for 12h to obtain 99.2g of the dried catalyst; 90.0g of the dried catalyst, 4.5g of cysteine, 9.0g of glutamic acid and 900.0g of ultrapure water were heat-treated and stirred at 220°C for 6h to obtain a product system, the product system was separated, and the wet solid was washed with ultrapure water several times until the pH of the solution was close to neutral, dried at 80°C for 24h, and then calcined in a muffle furnace, heated to 245°C at a heating rate of 0.5°C / min in a nitrogen atmosphere and calcined for 4h, and then heated to 520°C at a heating rate of 5.0°C / min and calcined for 8h to obtain the target catalyst for standby use.

[0085] Examples I-2 to I-5

[0086] Based on Example I-1, the other conditions were kept unchanged, and only the amounts of cysteine ​​and glutamic acid were changed.

[0087] Examples I-6 to I-11

[0088] Based on Example I-1, the other conditions were kept unchanged, and only the types of S-containing amino acids and organic nitrogen sources were changed.

[0089] Examples I-12 to I-17

[0090] Based on Example I-1, the other conditions were kept unchanged, and only the type and amount of solvent were changed.

[0091] The specific modification process parameters of Examples I-1 to I-17 are shown in Table 1.

[0092] Comparative Example I-1 Catalyst without modification

[0093] Take 100.0 g of commercial Pd / C catalyst GX-20240907-1, heat it to 120° C. in a N 2 atmosphere and dry it for 12 h to obtain 99.2 g of the dried catalyst for later use.

[0094] Comparative Example 1-2 Catalyst is modified only with an organic nitrogen source

[0095] Take 100.0g of commercial Pd / C catalyst GX-20240907-1, heat it to 120℃ in N2 atmosphere and dry it for 12h to obtain 99.2g of dried catalyst; take 90.0g of dried catalyst, 9.0g of glutamic acid and 900.0g of ultrapure water for heat treatment, stir at 220℃ for 6h to obtain a product system, separate the product system, wash the wet solid with ultrapure water several times until the pH of the solution is close to neutral, dry it at 80℃ for 24h, and then calcine it in a muffle furnace, heat it to 245℃ in nitrogen atmosphere at a heating rate of 0.5℃ / min and calcine it for 4h, then heat it to 520℃ at a heating rate of 5.0℃ / min and calcine it for 8h to obtain the catalyst for use.

[0096] Comparative Example 1-3 Catalyst modified only with S-containing amino acid

[0097] Take 100.0g of commercial Pd / C catalyst GX-20240907-1, heat it to 120℃ in N2 atmosphere and dry it for 12h to obtain 99.2g of dried catalyst; take 90.0g of dried catalyst, 4.5g of cysteine ​​and 900.0g of ultrapure water for heat treatment, stir at 220℃ for 6h to obtain a product system, separate the product system, wash the wet solid with ultrapure water several times until the pH of the solution is close to neutral, dry it at 80℃ for 24h, and then calcine it in a muffle furnace, heat it to 245℃ at a heating rate of 0.5℃ / min in a nitrogen atmosphere and calcine it for 4h, then heat it to 520℃ at a heating rate of 5.0℃ / min and calcine it for 8h to obtain the catalyst for use.

[0098] Comparative Example I-4 Catalyst is modified only with an inorganic sulfur source

[0099] Take 100.0g of commercial Pd / C catalyst GX-20240907-1, heat it to 120℃ in N2 atmosphere and dry it for 12h to obtain 99.2g of dried catalyst; take 90.0g of dried catalyst, 4.5g of concentrated sulfuric acid and 900.0g of ultrapure water for heat treatment, stir at 220℃ for 6h to obtain a product system, separate the product system, wash the wet solid with ultrapure water several times until the pH of the solution is close to neutral, dry it at 80℃ for 24h, and then calcine it in a muffle furnace, heat it to 245℃ at a heating rate of 0.5℃ / min in a nitrogen atmosphere and calcine it for 4h, then heat it to 520℃ at a heating rate of 5.0℃ / min and calcine it for 8h to obtain the catalyst for use.

[0100] Example 2

[0101] Take 100.0g of commercial Pd / C catalyst FD-0598 (granular catalyst, Pd loading is 0.1%, co-catalyst components are Fe and Ni, Pd content in the metal components is 63%, specific surface area is 536.2m 2 / g) was heated to 30°C in a vacuum atmosphere and dried for 48h to obtain 99.6g of the dried catalyst; 90.0g of the dried catalyst, 4.5g of methionine, 9.0g of lysine and asparagine and 900.0g of acetonitrile were heat-treated and stirred at 150°C for 24h to obtain a product system, the product system was separated, and the wet solid was washed with acetonitrile several times, dried at 60°C for 36h, and then calcined in a muffle furnace, heated to 200°C at a heating rate of 0.5°C / min in a nitrogen atmosphere and calcined for 12h, and then heated to 400°C at a heating rate of 4.0°C / min and calcined for 24h to obtain the target catalyst for standby use.

[0102] Example 3

[0103] Take 100.0g of commercial Pd / C catalyst Hy-3706-15 (granular catalyst, Pd loading is 1.0%, co-catalyst components are Co, Ag and Au, Pd content in metal components is 91%, specific surface area is 884.2m2 / g), heat to 60°C in Ar atmosphere and dry for 36h to obtain 99.4g of dried catalyst; take 90.0g of dried catalyst, 4.5g of cystine, 9.0g of arginine and 900.0g of ethanol for heat treatment, stir at 180°C for 18h to obtain a product system, separate the product system, wash the wet solid with 75% ethanol several times, dry at 100°C for 24h, and then calcine in a muffle furnace, heat to 450°C in Ar atmosphere at a heating rate of 0.5°C / min and calcine for 8h to obtain the target catalyst for use.

[0104] Catalysts are used in fixed bed hydrogenation processes:

[0105] The granular catalyst was loaded into a fixed bed reactor, equipped with 1,2,4-trichlorobenzene solution, and H2 as the reaction gas. The reaction space velocity was controlled to be 1.0 h -1 The reaction temperature was 200°C, the hydrogen / 1,2,4-trichlorobenzene molar ratio was 20, the 1,2,4-trichlorobenzene solution and hydrogen underwent a hydrogenation reaction over the catalyst bed to obtain a dechlorinated product, and the reaction liquid was collected for GC (gas chromatography) analysis.

[0106] The modification processes of I-1 to I-17 are listed in the following table:

[0107] Table 1 Catalyst sulfur modification process parameters

[0108]

[0109]

[0110] The catalysts prepared in Examples I-1 to I-17, Example 2, Example 3 and Comparative Examples I-1 to I-4 were used in a fixed bed hydrogenation process, and the reaction results of the catalytic hydrodechlorination were listed in the following table:

[0111] Table 2 Comparison of catalyst results for fixed bed catalytic hydrodechlorination reaction

[0112]

[0113] From the data in Table 1, it can be seen that when the unmodified Pd / C catalyst is used for catalytic hydrodechlorination reaction, although the conversion rate of the reaction is high, the selectivity of low-halogen products is poor; although the selectivity of the catalyst modified by the inorganic sulfur source is improved, the conversion rate decreases significantly; the selectivity stability of the catalyst modified only with S-containing amino acids is significantly improved, but the conversion rate also decreases greatly; the selectivity and life of the catalyst modified only with amino acids are improved, but the amplitude is not obvious. The present application uses a combination of S-containing amino acids and amino acids to modify the Pd / C catalyst, which can greatly improve the selectivity of low-halogen products, especially dichlorobenzene, and can effectively improve the hydrodechlorination life of the catalyst, which has extremely high commercial significance.

[0114] Example II

[0115] Take 100.0g of commercial Pd / C catalyst KR-240621 (powdered catalyst, Pd loading is 1.5%, co-catalyst components are Cu and Ni, Pd content in the metal components is 59%, specific surface area is 1015.8m 2 / g) was heated to 90°C in a He atmosphere and dried for 24h to obtain 99.1g of the dried catalyst; 90.0g of the dried catalyst, 4.5g of cysteine ​​and methionine, 9.0g of glycine and 900.0g of a mixed solution of methanol and isopropanol were heat-treated and stirred at 200°C for 10h to obtain a product system, the product system was separated, and the wet solid was washed with methanol several times, dried at 120°C for 8h, and then calcined in a muffle furnace, heated to 300°C in a He atmosphere at a heating rate of 2.0°C / min and calcined for 2h, and then heated to 550°C at a heating rate of 6.0°C / min and calcined for 6h to obtain the target catalyst for standby use.

[0116] Comparative Example II - Catalyst without modification

[0117] Take 100.0g of commercial Pd / C catalyst KR-240621 (powdered catalyst, Pd loading is 1.5%, co-catalyst components are Cu and Ni, Pd content in the metal components is 59%, specific surface area is 1015.8m 2 / g) was heated to 90°C in a He atmosphere and dried for 24h to obtain 99.1g of the dried catalyst for later use.

[0118] Example 4

[0119] Take 100.0g of commercial Pd / C catalyst XM-24039-7 (powdered catalyst, Pd loading is 2.0%, co-catalyst components are Fe, Cu and Ni, Pd content in the metal components is 72%, specific surface area is 1201.3m 2 / g) was heated to 150°C in a Ne atmosphere and dried for 4h to obtain 99.7g of the dried catalyst; 90.0g of the dried catalyst, 4.5g of acetylcysteine, 9.0g of glycine and 900.0g of a methanol mixture were heat treated and stirred at 250°C for 2h to obtain a product system, the product system was separated, and the wet solid was washed with methanol several times, dried at 150°C for 2h, and then calcined in a muffle furnace, heated to 245°C in a Ne atmosphere at a heating rate of 0.5°C / min and calcined for 4h, and then heated to 600°C at a heating rate of 10.0°C / min and calcined for 2h to obtain the target catalyst for standby use.

[0120] Catalysts are used in kettle hydrogenation process:

[0121] 30g of powdered catalyst, 150g of 1,2,4-trichlorobenzene and 400g of 5wt% NaOH aqueous solution were added to a tank reactor, hydrogen was introduced into the reactor, the temperature was raised to 100°C, the pressure was 0.8MPa, and a hydrogenation reaction was performed to obtain a dechlorinated product. After the reaction was completed, the gas was filtered and GC analysis was performed.

[0122] The catalysts prepared in Example II, Comparative Example II and Example 5 were used in a kettle hydrogenation process, and the reaction results of the catalytic hydrodechlorination were listed in the following table:

[0123] Table 2 Comparison of the results of the catalysts used in the autoclave catalytic hydrodechlorination reaction

[0124]

[0125] It can be seen from the above results that the method of the present application can be used to modify various commercial Pd / C catalysts. The obtained catalyst has improved catalytic activity and stability and can be used not only in fixed bed reactors but also in kettle reactors, and can improve the selectivity of hydrodechlorination.

[0126] Embodiment Example I-18-24

[0127] The calcination temperature program was changed on the basis of Example 1, and the prepared catalyst was used for fixed bed catalytic hydrodechlorination. The results are as follows:

[0128] Table 4 Comparison of catalyst results for fixed bed catalytic hydrodechlorination reaction

[0129]

[0130]

[0131] It can be seen from the data in Table 4 that the two-stage heating is beneficial to improving the stability of the catalyst, while the slow heating is helpful to improve the selectivity of the product.

[0132] Examples 17-24

[0133] On the basis of Example 1, 1,2,4-trichlorobenzene was replaced with other halogenated organic compounds, and the fixed bed catalytic hydrogenation process parameters were changed. The results were as follows:

[0134] Table 5 Comparison of catalyst results for fixed bed catalytic hydrogenation reactions

[0135]

[0136]

[0137] It can be seen from the data in Table 5 that the Pd / C catalyst prepared by the modification method of the present invention can improve the selectivity of dehalogenated products for the catalytic hydrodehalogenation reaction of various halogenated organic compounds. In particular, for benzene substituted with multiple chlorine atoms, one or two chlorine atoms can be selectively removed to improve the selectivity of dichlorobenzene.

[0138] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the substantial technical content of the present invention. The substantial technical content of the present invention is broadly defined in the scope of the claims of the application. Any technical entity or method completed by others, if it is exactly the same as that defined in the scope of the claims of the application or an equivalent variation, will be deemed to be included in the scope of the claims.

[0139] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as reference separately. In addition, it should be understood that after reading the above content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for modifying a Pd / C catalyst, the method comprising the following steps: (1) subjecting the Pd / C catalyst to a first drying treatment; (2) mixing the catalyst obtained in step (1), an S-containing amino acid or its derivative, an organic nitrogen source and a solvent and subjecting them to heat treatment, wherein the mass ratio of the S-containing amino acid or its derivative, the organic nitrogen source, the catalyst and the solvent is 0.01-0.1:0.05-0.5:1:5-50; (3) separating, washing and performing a second drying treatment on the catalyst obtained in step (2); (4) calcining the catalyst obtained in step (3) to obtain a modified Pd / C catalyst.

2. The method according to claim 1, characterized in that The Pd loading in the Pd / C catalyst is 0.1-2.0% and the specific surface area is ≥400m 2 / g, and / or The Pd / C type catalyst contains a promoter component, which includes one or more of Pt, Ni, Co, Au, Ag, Cu, and Fe, wherein the Pd content is >50%, based on the total weight of the metal components.

3. The method according to claim 1 or 2, characterized in that The S-containing amino acid or its derivatives include one or more of cysteine, methionine, cystine, acetylcysteine, sulfo-cysteine, benzyl-cysteine, ethyl-cysteine, (2-carboxyethyl)-cysteine, glutathione, and adenosylmethionine; and / or The organic nitrogen source includes one or more of glutamic acid, lysine, glycine, histidine, asparagine and arginine.

4. The method according to claim 1 or 2, characterized in that: In the step (2), the solvent used for the heat treatment includes one or more of water, methanol, ethanol, isopropanol, and acetonitrile; and / or The heat treatment temperature is 150-250° C.; and / or The heat treatment reaction time is 2 to 24 hours.

5. The method according to claim 1 or 2, characterized in that: The first drying temperature is 30 to 150° C., and the first drying time is 4 to 48 hours; and / or The second drying temperature is 60 to 150° C., and the second drying time is 2 to 36 hours; and / or The calcination temperature is 400-600° C., and the calcination time is 2-24 hours.

6. The Pd / C modified catalyst prepared by the method according to any one of claims 1 to 5.

7. A method for hydrodehalogenation of halogenated organic matter, the method using the Pd / C type modified catalyst according to claim 6 for reaction.

8. The method according to claim 7, wherein the method is carried out by a kettle hydrogenation process, wherein the halogenated organic matter is subjected to a hydrodehalogenation reaction with hydrogen in the presence of the Pd / C type modified catalyst and a base.

9. The method according to claim 7, wherein the method is carried out by a fixed bed hydrogenation process, wherein the halogenated organic matter is subjected to a hydrodehalogenation reaction with hydrogen in the presence of the Pd / C type modified catalyst.

10. The hydrodehalogenation product prepared by the method according to any one of claims 7 to 9.

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